I use my Viking Emerald 118 for FMQ and straight line quilting. I have not had a ton of FMQ practice, so most of my completed projects have all been straight lines and gentle curves done with a walking foot. The largest I have done on my machine is a baby quilt, and I am going to try and do a lap size TATW quilt in the near future. I would love to have a long arm some day, but for now, if I need a long arm, I have a local shop that will rent theirs out and give you instructions for using it. Haven't gone there yet - can't wait to try it on the top I am currently piecing.
PS I have seen on Leah Day's website that she uses a hanging system to hold the weight of a large quilt when FMQ on a domestic machine. It looks like it would work well - has anyone here tried it? I plan to at some point...